A microplate reader is used to detect or measure the response of biological samples to a stimulus disposed on a microplate. The microplate includes a predetermined number of cells configured in a two-dimensional array, and a sample of biological material may be disposed in each cell.
The stimulus may be exposure to radiation (such as light source), a chemical, an electrical field, or an interaction with another biological material. In some cases, the response includes generation of light (for example, if the biological sample fluoresces in response to the stimulus), absorption of particular wavelengths of light, or production of a byproduct. The presence and/or magnitude of one or more such response(s) may be measured using the microplate reader.
Some microplate readers measure only a particular characteristic of the response to stimulus, for example, only emissions due to fluorescence or absorption of light. In contrast, a multi-mode microplate reader measures different characteristics of the responses to a particular stimulus including a change in light absorbance and/or luminescence (fluorescence, chemiluminescence, bioluminescence, electroluminescence, thermoluminescence, and the like) by the sample. Such a multi-mode microplate reader exposes the sample to the stimulus and uses one or more filters to detect the different types of responses.
In addition, the multi-mode microplate reader typically includes apparatus that provides the stimulus to the biological sample including electrical probes and/or one or more micro-pipette(s) for delivering a predetermined amount of one or more reagent(s). The multi-mode microplate reader also includes one or more filters and one or more sensors. Each type of filter allows particular wavelengths of light emitted by the stimulated sample to pass therethrough before being detected by the sensor. The sensor may be photo-sensor or a digital camera chip, such as a charge-coupled device, a photomultiplier tube, an avalanche photodiode, and the like.
In operation, a user defines an assay protocol that specifies the type of sample to be tested, a layout of the microplate on which samples will be disposed, the stimulation to be provided to each sample, reagents and other material that will be used during testing, and the types of response to be measured. The protocol may associate for each type of response one or more optical filters to position in the light path between the sample and the sensor.
Once the protocol is defined, the microplate reader may be operated to carry out the protocol with one or more microplates. Further, assay kits associated with the protocol may be commercially procured or assembled that include the microplate(s), reagents, and other materials necessary to carry out the protocol. Once developed, the protocol may be stored on a storage media associated with the microplate reader, and retrieved and executed one or more times as necessary
For the protocol to be carried out without errors and without interruption, it is important that the filters necessary for the protocol are loaded into the microplate reader, and sufficient quantities of consumable materials that comprise the assay kit associated with the protocol are available.